We are studying the structure and function of extracellular matrix components. Our data define how the components of skin, cartilage and basement membrane interact with each other to assemble into supramolecular complexes. The basement membrane collagens, proteoglycans, cell attachment proteins and other glycoproteins of the respective tissues bind to each other in a highly specific manner and in precisely stoichiometry to form ordered complexes. These interactions define the structure and function of the matrix in tissue morphogenesis, in wound repair and in certain diseases. Various biological activities of epithelial cells are controlled by basement membrane components. The adhesion and growth of neonatal Schwann cells is specifically increased several-fold by laminin and the cells appear more differentiated and elongated. B16 Melanoma cells produce more pigment in vitro when cultured on basement membrane substrates. These and other studies on cultured cells indicate that the matrix components may regulate tissue formation and repair by determining which cells attach and proliferate.